Quantitative damage depth proﬁles in arsenic implanted HgCdTe C. Lobre a,⇑ , D. Jalabert b , I. Vickridge c , E. Briand c , D. Benzeggouta c , L. Mollard a , P.H. Jouneau b , P. Ballet a a CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9, France b CEA-INAC/UJF-Grenoble 1 UMR-E, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9, France c Institut des NanoSciences de Paris, UMR 7588 du CNRS, Universite de Pierre et Marie Curie, Paris, France article info Article history: Received 28 June 2013 Received in revised form 31 July 2013 Available online 13 August 2013 Keywords: HgCdTe Ion implantation Damage proﬁles RBS-c abstract Rutherford backscattering experiments under channeling conditions (RBS-c) have been carried out on Hg 0.77 Cd 0.23 Te (MCT) layers implanted with arsenic. Accurate damage proﬁles have been extracted through a simple formalism for implanted and annealed layers. Quantitative damage proﬁles are corre- lated with structural defects observed by bright-ﬁeld scanning transmission electron microscopy (BF-STEM) and chemical composition measured by secondary ion mass spectrometry (SIMS). Evolution of damage for increasing ion implantation ﬂuence has been investigated by these three complementary techniques. Evidence is found of irradiation induced annealing during implantation. A fast damage recov- ery has been observed for post-implantation thermal anneals. In the case of an implanted layer annealed during 1 h, the damage proﬁle, associated with arsenic concentration measurements, indicates the presence of complexes involving arsenic. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Mercury cadmium telluride (MCT) is a semiconductor alloy widely used for infrared photo-detection. Therefore, accurate elec- trical doping of this compound with a good spatial control is of critical importance for the fabrication of devices. The p-on-n pho- todiode architecture is especially attractive as it leads to excellent device performance and, in particular, low dark currents allowing high working temperatures [1]. This architecture requires a shal- low, well-controlled zone of electrically active p-type extrinsic dopant. Arsenic is the most used p-type doping species for this architec- ture and ion implantation provides a suitable method to produce the shallow localized layer. Nevertheless, an important challenge still needs to be overcome in order to activate the implanted ar- senic: a strong electrical n-type doping region is always observed in implanted MCT for any implanted species. In addition, the donor concentration can be greater than the impurity concentration [2]. This electrical activity is ascribed to irradiation related damages and needs to be fully removed in order to achieve a well-controlled p-type doped region. Furthermore, structural defects are known to induce poor device performance. As a consequence, ion implanta- tion damage formation and recovery have been extensively studied in MCT by TEM [3,4], RBS-c [5–8], electrical measurements [9] and X-ray diffuse scattering [10]. Among these techniques, RBS-c provides quantitative information on structural defects created by ion implantation. Combined with the localized information ob- tained from BF-STEM and chemical analysis provided by SIMS, it allows an accurate understanding of the defect formation, migra- tion and annihilation. However, despite a strong technological importance, few studies of damages due to implantation of arsenic in MCT have been reported up to now and, to our knowledge, none of them has used RBS-c. This work reports our study of damages induced by arsenic implantation in MCT and their evolution during post-implant anneals. In the ﬁrst part of this paper, the high sensitivity of RBS-c to defects is used to extract damage proﬁles on as-grown samples. In the second part, the RBS-c experiments are comple- mented by BF-STEM observations which provide direct visualiza- tion of implantation related defects, and SIMS measurements of arsenic concentration proﬁles, to investigate the inﬂuence of the implanted ﬂuence, and to study damage evolution during annealing. 2. Material and methods Epitaxial Hg 0.77 Cd 0.23 Te (MCT) layers of 6 lm thick were grown on CdZnTe (1 1 1) B substrate by horizontal slider liquid-phase epi- taxy (LPE) from a Te-rich solution [11]. Crystals were subsequently implanted in an off-axis random direction with arsenic ions at an energy of 360 keV and with ﬂuences ranging from 5  10 13 to 2  10 15 ions cm 2 . Post-implant anneals were performed at tem- perature in the range of 400–450 °C under mercury saturated pres- sure. Heat up and cool down times were about 10 and 40 min, respectively. Annealing step times were varied from 30 s to 5 h. 0168-583X/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nimb.2013.07.019 ⇑ Corresponding author. Tel.: +33 438784148. E-mail address: clement.lobre@cea.fr (C. Lobre). Nuclear Instruments and Methods in Physics Research B 313 (2013) 76–80 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb